This invention relates generally to self-organizing mesh networks. In particular, the invention relates to a wireless handheld configuration device and an operating mode that allows the handheld device to communicate with a selected device of a self-organizing mesh network.
A self-organizing mesh network is a communications network made up of individual devices that are configured to use other networked devices to reliably pass data from one point to another. Ideally, each device has many paths available for passing data to its intended destination. When a new device joins the network, a network manager provides the new device with a schedule which the new device will use to talk to other devices in the network. Each device in the network is provided with “slots” (specific times and radio frequencies) for passing data to or from one or more “children” and one or more “parents”. Using different times and frequencies allow many devices to pass messages in the same space without collisions. Frequency hopping also helps to secure the data that is being passed in the network. Secured self-organizing networks frequently employ authentication and encryption to further protect the network. While these attributes result in a very secure and reliable network, they also make it difficult and inefficient to use a wireless hand held configuration device in the network, because it may take several minutes for the device to be recognized in the network and to establish necessary communication links to the wireless devices to be configured. The presence of such a “transient” participant in the network can also disturb the network, making it less efficient and more power hungry as the device joins, moves around in and un-joins the network.
Secure self-organizing mesh networks of the type in question use a process known as “joining” to incorporate new devices into the secured network. During the joining process, a number of information exchanges and configurations take place.
The new device uses a network pre-determined channel to discover similar devices within radio range. These are the existing network nodes the new device has available to it in order to gain membership into the network. The presence of each device within earshot is recorded. Later in the joining process, the new device will provide its “neighbor” list to the network manager so that the network manager can determine the links that must be established to allow the new device to participate in the network. The network manager also needs to be aware of “excess” neighbors not needed for the new device to communicate on the network. The network manager must ensure that the newly established links do not interfere with the pre-existing links of these neighbor devices.
The new device uses its pre-configured security information to decode a joining message from the manager and sends back the expected security response along with other information necessary for the manager to establish links from the new device to other devices in the network.
The new device and the new parents and children receive and implement configuration information from the network manager to establish the required links. The new device is then fully joined and participating in the network.
In most networks, the joining process described above happens only when new devices join the network. The process may take some time (15 to 20 minutes depending on the network) but since it happens very infrequently, the impact is minor. A wireless handheld device used to interrogate and configure devices in the network may, however, join many times as it is moved around to configure different devices. It is not practical for this type of device to join the network as if it were a standard fixed position device. Not only would this be extremely inconvenient for the user to wait many minutes for the handheld device to join the network, but the frequent joining and un-joining will impact network performance. There is a need for a different method for allowing special devices (such as a wireless handheld configuration device) that are not fixed in the network to join and leave a self-organizing mesh network.